How to set the background color of a repeating card?

I have a repeating card component bound to a data variable collection and would like to set the background color of individual cards based on a field in the data variable? Is this possible and if I need a formula then an example would be very helpful. I am a newbie and have watched several videos that seem to be for an earlier version. Thanks David

When choosing component’s background, there is an option to bind it to a formula: